Method of dezincing



Feb. 17. 1925.

W. JOB

METHOD OF DEZINCING Filed July 1920 IN VEN TOR. l W/J 9 S. PIN Ky.

1 5 ATTORNEY.

Patented Fa. 17, 1925.

UNITED STATES WOLFGANG JOB, 0F BERLTN-DAHLEM, GERMANY.

METHOD OF DEZINCING.

Application filed July 9, 1920. Serial No. 395,093.

To all whom it may concern:

Be it known that I, VVQLFGANG Jon, a citizen of the German Republic, residing at Berlin-Dahlem, Ehrenbergerstrasse 33, Germany, have invented certain new and useful Improvements in a Method of Dezincing, of which the following is a specification. I

The invention relates to a method for removing volatilizable metal, particularly zinc, from slags, ores, and the like, containing the metal, by volatilizing the metal. It has previously been proposed to smelt such materials containing zinc ina blast furnace, with the object of. obtaining a liquid slag, while the zinc was to be volatilized in the form of vapor. Experiments have, however, demonstrated that it is not possible to obtain a sufiicient volatilization of the zinc by applying this method, without further treatment. Only or less of the zinc content of the material could be extracted by following this method, because of the fact that the oxide of zinc, which was formed within the charge by reducing the ore of zincto vapor and by reoxidizing the vapor, was easily absorbed. Metallic zinc vapor has a great aflinity for oxygen and will combine therewith, if there is any available oxygen, even if carbon dioxide is present. This zinc oxide is a solid body and when formedby reoxidization of the .ZHIO vapor part of the same was easily absorbed by the dropping slag. Also it was in part precipitated as a powder on the upper layers of the charge, sank down with the charge and was absorbed again. Also part- 1 it was absorbed by the liquid bath of s ag on the furnace hearth.

The present invention has for its object the production of a method whereby a rather complete dezincing of slag and other materials may be obtained, or to state the matter more broadly, since the invention applies also to the extraction of volatile metals other than zinc, it may be said that the object of the invention is the production of an improved method for removing volatile metals from materials containing same.

In order that the invention may be more clearly understood attention is directed hereby to the accompanying drawing in which the figure represents a vertical section through a blast furnace in which the method may be carried out.

In practicing the invention, as applied to the removal of zinc from slag or other material containing the same, I proceed as follows. When the blast furnace is blown in, it is charged with a thick layer of coke or other suitable reducing fuel and a definite quantity of the material to, be dezinced is charged thereon. The layer of coke may be charged on the hearth 1 to such a height as is indicated, for example, in the drawings, in which the top of the layer of coke is indicated at 2. A definite charge of the material which is to be dezinced or treated is indicated at 3. One of the tuyeres for the air blast is indicated at 4, and one of the openings through which the slag will run out is indicated at 5, the furnace being a charged through the top at 6. The water jacket for the furnace is indicated at 7. Reference to the drawing is made merely to make the description of the process clearer, the invention not loeing limited to the use of the particular apparatus indicated.

The material containing the zinc is melted by the heat produced by the. burning of the fuel under the application of the airblast, and liquid drops of slag trickle or passdownwardly through the hot layer of coke or other reducing fuel used. Because of the contact of these drops of slag with the hot coke the zinc is extracted'in the form of metallic vapor and rises with the gas stream. This Zinc vapor will not be oxidized to the oxide of zinc, since a reducing atmosphere is maintained throughout the charge.v

The gases pass out of the furnace through the conduit indicated at 8 by which they may be carried to a combustion chamber (not illustrated), in which air will be supplied to oxidize the vapor to provide oxide of zinc for commercial use,-in the usual a second layer of material to be dezinced,

10, is charged upon the layer of coke 9. The layer of coke 9 should be suflicient in thickness to compensate for the sinking of the charge beneath the same, so that the reducing atmosphere ma be maintained through the second layer of material to be dezinced,

10. In this manner charging may be con tinued so as to continuously maintain the conditions necessary for complete dezincin of the material. Additional layers of fuel andmaterial to be dezinced in alternate arrangement are indicated in the drawing as charged above the layer of material 10.

The quantity of the material containing the zinc, which is to be charged on each layer of coke, must be regulated in due proportion to the thickness of the layer'of the coke. The melted drops of slag, which pass downwardly through the furnace on their way to the slag tap 5, must find a quantity of red hot coke sufficient for their complete dezincing. I r

If the quantity of material to be dezinced is toogreat in proportion to the quantity of coke, the drops of slag trickle too rapidly through the glowing char e of coke and the dezincing remains incomp etc in spite of the reducing atmosphere.

A certain quantity of fuel may, if desired, be mixed'with the charge or charges containing zinc. It is, however, essential that a layer of fuel be constantly maintained beneath each layer of material through which the liquid slag must flow and by which the reducing atmosphere is maintained.

It is especially advantageous to practice the invention in connection with materials containing zinc, and particularly for sla'gs which contain sulphur. If slags containing sulphur and zinc are treated in the usual manner in a blast furnace, the greater part of the sulphur is burned and escapes in the form of sulphurous acid into the air, this passing through the filters which are ordinarily provided for the oxide of zinc, in connection with, or adjacent to the combustion chamber referred to. In such practice not only is the sulphur lost but also injuries to vegetation may result which eventually may make it impossible to continue the operations.

If, however, slag containing zinc and sulphur is treated in accordance with the present invention, no sulphurous acid escapes with thegases. Because of the reducing atmosphere which is maintained throu hout the charge the sulphur is not oxidize but is carried down through the. furnace with the slag and passes into a matte. It is, of course, assumed that the material which is to be dezinced contains enough iron for forming a matte which is the fact in almost all cases. Otherwise a corresponding amount of iron must be added. The matte contains iron, and all of the copper and precious,-

metals which may have been contained in the slag and practically all ofthe sulphur. The slag and matte pass out through the slag tap 5, and may fall into, a suitable settler (not shown), in which the matte, be-

ing of higher specific gravity than the slag, separates therefrom. The iron concentrated in the matte may be utilized, after roasting, as iron ore.

To most of the usual materials, no flux need be added. It may be advantageous, however, to add certain fluxes, such as limestone for making the smelting and the extraction of the zinc easier.

As stated above the method may also be applied to ores and materials contaimng other volatile metals such, for instance as tin, lead, antimony and arsenic.

It should be understood that the invention is not limited strictly to the details which have been particularly described but that the same is as broad as is indicated by the accompanying claims.

"What I claim is:

1. The method of removing volatilizable metal from materials containing the same, such as slag and ores, which comprises, maintaining a comparatively thick charge of reducing fuel beneath the charge of material to be treated, in a furnace introducing air into and causing combustion of said charge to maintain the same and the charge thereabove, at a temperature such as to smelt the material and volatilize the metal, the fuel charge being sufficiently thick to maintain a reducing atmosphere throughout the entire mass of fuel and material to be treated, and causing molten drops of the material to pass through the burning fuel, the metal being volatilized and passing off, the proportion of the material and fuel charged being so regulated that the dropping molten material will come into contact with a sufficient quantity of fuel to effect the volatilization of the metal.

2. The method of removing volatilizable metal from materials containing the same, such as slag and ores, which comprises, maintaining a comparatively thick charge of reducing fuel beneath'the charge of material to be treated, in a blast furnace int-roducing air into and causing combustion of said charge to maintain the same and the charge thereabove, at atemperature such as to smelt the material and volatilize the metal. the fuel charge being sufficiently thick to maintain a reducing atmosphere throughout the entire mass offuel and material to be treated, and operating the furnace to cause" molten drops of the material to pass through the burning fuel to volatilize the metal, and permitting the volatilized metal to pass ofi.

3. The method of removing volatilizable metal from materials containing the same, such as slag and ores, which comprises, maintaining in a flu'nace layers of material to he treated and of fuel, each layer of fuel beneath a layer of material, and operatmg the furnace b introducingair into and Ill) causing combustion of the lower layer of fuel to melt the material and cause molten drops thereof to pass downwardly, each layer of fuel-being of such a; thickness that a reducing atmosphere will be maintained throughout the entire charge, the metal being volatilized as the molten drops of slag pass through the burning fuel.

a. The method of removing zinc from materials containing the same, such as slag and ores, which comprises, maintaining a comparatively thick charge of reducing fuel beneath the charge of material to be treated, in a furnace introducingair into and causing combustion of said charge to maintain the same and the charge thereabove, at a temperature such as to smelt the material and volatilize the zinc, the fuel charge being sufiiciently thick to maintain a reducing atmosphere throughout the entire mass of fuel and material to be treated, and causing molten drops of the material to pass through the burning fuel, the zinc being volatilized and passing off, the proportion of the material and fuel charged being so regulated that the dropping molten material will come into contact with a sufiicient quantity'of fuel to effect the volatilization of the zinc.

5., The method of removing volatilizable metal from materials containing the same, such as slag and ores, which comprises, charging into a blast furnace a comparatively thick charge of reducing fuel, charging thereon a layer of material to be treated, operating the furnace by introducing air into and causing the combustion of said fuel charge to bring the fuel to and maintain it at a suflicient temperature to volatilize the said metal in the material, the

thickness of the fuel charge being suflicient to maintain a reducing atmosphere throughout the entire charge of fuel and material, causing molten drops of the material to pass through the burning fuel, the metal being volatilized, thereafter charging a quantity of reducing fuel sufiicient to compensate for the lowering of the original charges due to the burning of the fuel and a charge of fresh material to be treated upon that, and continuing such charging from time to time as required, each charge of fuel being sufficient in quantity to maintain a reducing atmosphere throughout the layer of material to be treated charged upon the same.

. G. The method of removing volatilizable metal and sulphur from materials containing the same, which comprises, maintaining a comparatively thick charge of reducing fuel beneath the charge of material to be treated, in a furnace introducing air intoand causing combustion of said charge to maintain the same and the charge thereabove, at a temperature such as to volatilize the metal, the fuel charge being sufliciently thick to maintain a. reducing atmosphere throughout the entire mass of fuel and material to be treated, and causing molten drops of material to pass through the burning fuel, the metal being volatilized and passing off, and the sulphur being carried along with the slag and passing into a matte.

,"In testimon whereof I allix my signature in presence 0 two witnesses.

lVOLFGANG JOB. Witnesses:

FRAU ELISABETH SPREIKE, one. MAHLER, HATTIE .laoouson. 

